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` (No Model.)v

2 Sheets-Sheet 1.

E. WESTN.v

. RHEOSTAT.

- Patented Aprl 22,1884.

' w @annum l (No Model.) 2 Sheets-Sheet 2.

' E. WESTON.

RHBOSTAT, N0. 297,324. y Paten-ted Apr. 22, 1884.

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N. PETERS Phmumgmphen wnhmguw, nA c.

UNITED STATES PATENT Critica..

EDWARD WESTON, OF NEWARK, NEW JERSEY, ASSIGNOR TO THE UNITED STATES ELECTRIC LIGHTING COMPANY, OF NEW YORK, N. Y.

RH EOSTAT.

SPECIFICATION forming part of Letters Patent No. 297,324-, dated April 22, 1884.

(No model.)

To @ZZ whom it may concern:

Be it known that I, EDWARD WEsToN, a subject of the Queen of Great Britain, and a resident of Newark, in the county of- Essex and State of New Jersey, have invented certain new anduseful Improvements in Rheostats, of which the following is a' specification, lreference being had to the accompanying drawings, and to the letters and figures marked thereon.

The subject of my present invention is a portable rheostat or variable resistance capable of being used with electrical apparatus generally, but more especially designed for regulating the current passing through the fieldmagnet coils of one or more dynamo-electric machines, the current of which is'utilized for operating electric lamps, motors, or other devices.

The obj ect of the invention is mainly to simplify the construction .of the rheostat and to render it more compact and portable, and also to protect the coils from injury, as by careless handling, and from displacement and overheating. To this end I have constructed the rheostat in substantially the following manner: I employ a suitable number of thin boards or slabs of insulating material, upon which I wind uninsulated brass, German silver, or iron wire in spiral form, forming notches along the edges of the board for holding the wires in place. I form a pile of these boards with their coils, inserting between each two boards strips or blocks of insulating material, so that a space is left for the circulation of air. The pile of boards or slabs is bound together between heads of insulating material, any kind of clamping devices-such as screw rods and nuts-being suitable for this purpose. The whole is then secured to a board which serves as a cover to a box, into which the resistance-coils may be inserted. A circular series of contact-plates, which are connected consecutively with the coils, is arranged upon this cover, and a handle or key is placed so as to sweep over the plates'. The circuit-connections are made in the usual way. This general plan of construction secures many advantages, the apparatus being much more compact, less liable to injury or derangement, and much cheaper than any Others of the kind of which I am aware.

In order that the details of construction may be more fully understood, I will now describe the same by the aid ofthe accompanying drawings.

Figure l is afront view, in elevation, of the apparatus, showing the key or switch and the contact-plates. Fig. 2 is a central vertical section of the same. Fig. 3 is a top View of the resistance devices and their inclosing-case, the 6o top of the latter being removed. Figs. 4 and 5 are diagrams illustrating the plan ot' connection between the several coils and between the coils and the contact-plates.

A A are thin iiat boards or slabs of other insulating material. Along the edges of these boards are cut a series of notches, a c. A naked Wire, B, lof brass, German silver, or any other metal that is commonly employed for this purpose is then wound around the slabs 7c in the notches or indentations, and spirally, as shown in Fig. 2, the ends of the wire being secured in any proper manner, as by being passed through the slab, as atb b. A number of the slabs A are laid in a pile, strips C, of wood or other insulating material, being interposed between them. The slabs are kept in place by the end plates D D, rods E, and nuts c. The end plates D may be ordinary boards, flat or recessed; or they may be simple frames. They are securely fastened to a board or plate, F, which is fitted as a cover to a rectangular box, G, of just sufficient size and shape to contain the pile of resistance-coils. On the cover F is arranged a circular series of contact-plates, H, and a switch-lever with contact-springs f is pivoted in the center of the series.

L M are binding-posts set in cover F, and connected, respectively, with the end plate It of the series and to the switch lever or arm K. The coils formed by the wires B are connected up to form a continuous series. One end is connected to plate h, the other` to the plate h at thevopposite endof the series. From the wire B, where it passes from one slab Ato the 95 next,a connection is made to one of the plates H, these connections being in regular order, so that as the arm K is turned away from the plate h a gradually-increasing resistance will be introduced into the circuit formed through the rheostat. The plates H may be greater in number than the coils, and connections made IOO from them to intermediate parts of the coils, as shown in Fig. 5. The connections between the wire B and the plates H are by preference made byleading insulated copper wires, which pass from the plates, through the cover F to the rear of the pile of slabs, and connecting them to the wire B at the rear edges ot' the slabs A. The joints are by this means rendered more easy of access.

As stated above, an apparatus of this kind is adapted to varying the resistance of an electric circuit generally. rihe construction of this device, however, specially adapts it 'for use with dynamo machines having derived iield-circuits, as it may be placed close to the machines in shops, engine-rooms, and the like without danger ot' being injured by contact with other bodies or by oxidation.

The number and size ot' the slabs A will of course depend upon the capacity of the machine with which the rheostat is to be employed.

Having now described my invention, what I claim isl. The combination, with anumber of slabs or plates of insulating` material bound together in a bundle, with interposed strips of insulat ing material, and Wound with uninsulatcd resistance-coils, of a box or casing for containing the bundle, a removable cover-to which the bundle is secured, a series ot' contact-plates on the exterior ot' said cover and connected with the coils, and a key or shifting-contact for including more or less ofthe coils in an electric circuit, as set forth.

2. The combination of a number ot' plates or slabs, as A, wound With coils, the interposed strips or blocks, C, for keeping them apart and affording spaces for the circulation ot air, the end plates D and rods E, or other suitable devices for binding the plates A together, the cover or support F, and the series of contact-platesl arranged thereon and connected with the coils in substantially the n1an ner described.

In testimony whereof I have hereunto set my hand this 17th day of January, 1883.

EDWARD XVESTON.

fitnessesz RAYMOND F. BARNES, W. FRIsnY. 

